Eliminate ~ a Gazillion(tm) redundent calls of move_cost and map::has_flag( std::string("BASHABLE") ) from update_scent;
  * cache results to boolean arrays
  * pre-initialize "BASHABLE" and "REDUCES_SCENT"

This combined with previous vehicle and map optimizations makes 'wait' zip by at about a second
per 5 minutes, vs OMFG_SO_FRUSTRATINGLY_SLOW_I_LOST_COUNT (low end device)